1. Field of the Invention
The present invention relates to composite construction of a casing, Jacket, shell or housing of a rotary piston engine with a trochoidal-shaped dual-arc casing raceway and a triangular piston rotating upon an eccentric of an eccentric shaft and including sealing strips arranged in the corners of the triangular piston, such sealing strips riding along this casing raceway which consists of a layer of steel forming the casing raceway and an outer layer of an aluminum alloy cast around this layer of steel forming the mantle or casing raceway.
2. Description of the Prior Art
Such arrangements have a purpose, on the one hand to simplify production via avoidance of chip-removing, grinding machining of the raceway proceeding in a trochoidal shape, and on the other hand to obtain a hard, mantle or casing raceway resistant to impact stress or load via the radial sealing strips of the piston in a casing or housing mantle of aluminum alloy good for dissipating the heat.
In the prior art, U.S. Pat. No. 3,937,266-Cordone et al dated Feb. 10, 1976 discoses a method for application of wear-resistant coating involving a procedure of so-called transferred molding or transplant procedure according to which around a mold core forming the negative mold of the mantle or housing raceway there is built up a hard layer forming the mantle raceway via metal spraying, plasma spraying or in an electrochemical application procedure, which is removed and placed around a core identical with the aforementioned mold core which results in the inner tool of a cast mold for the housing mantle. The fluid or liquid aluminum pressed into the casting mold binds or connects itself with the layer forming the outer surface of the raceway, runway, path or course for engagement by the sealing strips of the triangular piston.
In order to obtain a better, most of all binding or connection withstanding the changing or variation of heat loading during operation between the highly carbonaceous or carbon-rich steel and the aluminum alloy, there was proposed to produce the layer forming the runway or raceway out of a steel band or strip which is welded together into a trochoidal-shaped ring into the outer side of which there is struck or rolled an arrow-type tooth means. The connection surface of the two metals is enlarged thereby and the housing mantle or shell consisting of aluminum is anchored better in the layer forming the runway or raceway (Japanese Patent Application No. Sho-52-123776 of Oct. 15, 1977 and Japanese Patent Application No. Sho-53-22383 of Feb. 28, 1978).
Via these measures, however, on the one hand, the difficulties which result via the greater heat expansion of aluminum with respect to the inner layer consisting of an iron alloy and on the other hand those resulting via the poor or inferior heat conduction of the inner layer, also cannot be eliminated via the described tooth means of the two materials, most of all not in the ranges or region of highest procedural temperatures. Accordingly, material cracks or fissures and layer separation can show up and be encountered especially around the seat of the spark plug. An important and considerably disadvantage additionally is that the heat transfer or conveyance to the cooling system as a whole is hindered, obstructed or restrained by the closed steel layer.